The invention relates to a frame, particularly a sidewall frame for pallets, composed of preferably plural frame bars that define a surface of the frame and to which a frame insert is secured in a manner that enables it to be loaded transversely within a plane of the frame.
A frame with the aforesaid features is generally known. The frame insert is secured in the frame such that after insertion it must be retained externally and is then riveted or welded. The joining techniques are performed in at least two work steps. Such frames are used in particular as side walls for pallets. These are articles that are manufactured on a relatively large scale. Under these circumstances, it is especially disadvantageous if high production costs have to be expended because of an onerous manufacturing process.
The object of the invention, by contrast, is to improve a frame with a frame insert having the aforesaid features in such a way that less time and expense are required for its production and production is simplified.
This object is accomplished in that the frame insert is form-fittingly interlocked with at least one frame bar transversely to the plane of the frame.
It is of importance for the invention that the structure is rendered stable merely by interlocking the frame insert together with the frame, which is composed of frame bars. No further welding or riveting of the frame insert to the frame is required, although this can be done as needed after interlocking to further improve the structural stability without any changes in the shapes involved Assembly is simplified by the fact that the frame insert can be mounted in the frame in one operation. Owing to this simplified assembly, the construction and the materials of the frame bars and the frame insert can be varied over a wide range at low cost The frame inserts can easily be pried out for cleaning or replacement without replacing the frame as well. The frame inserts are not damaged by mounting and removal and can be reused. This interlocking technique makes it possible to combine different materials without problems, particularly materials that can be welded only at widely different temperatures or not at all. The frame inserts can also be inserted and held in place with play, so that materials whose elasticity or expansion properties are different from those of the frame structure can be used as frame insert materials.
The frame can be implemented so that it is rectangular and its frame insert is interlocked with mutually parallel frame bars. The rectangular shape of the frame makes for especially easy mounting of the frame insert and enables various frames to be connected to one another, and, in the case of a palletizable container, to a rectangular pallet. Essentially, the frame insert need only be interlocked with opposite, parallel frame bars to hold it in place. The frame insert can easily be clicked into place and sits securely in either a one-part or a multi-part frame that can be made from a plurality of either straight- or miter-cut frame bars joined by weld seams or corner connectors.
It is advantageous to realize a frame in such manner that a frame bar is provided with a longitudinally extending locking recess in which the frame insert engages by an inserting edge. A longitudinally extending locking recess can be produced with little expenditure in a frame bar made, for example, of a hollow-profile section. If the locking recess extends over the entire frame bar, the arrangement of the insert in the frame can be varied if the insert is shorter than the frame bar. A frame insert that can be slid after being inserted in the frame can also be used. The inserting edge of the frame insert is easy to produce in this arrangement.
It is advantageous if the frame insert is a thin panel with insetting edges formed by tangent-bent portions. These can easily be made by bending or in a rolling process, for example in sheet stock. No complex shapes need be added.
In an advantageous embodiment of the frame, the locking recess is disposed on a frame-bar wall that faces a parallel frame bar. In this way, the frame insert can be mounted between the two frame bars. This makes it easier to obtain a good form-fitted seat. The structure has the same functionality, but its depth is smaller. This is especially desirable for palletizable containers because of the increased loading capacity gained from the smaller thickness of the frame sidewalls.
It is advantageous if the locking recess has the shape in cross section of a mating inserting edge which, if necessary, conforms to the adjacent surface of the frame bar comprising the locking recess. This ensures a good form-fit for the frame insert with the wall of the frame bar. The locking recess and the inserting edge meet to form a level surface. In this way, if goods to be carried should happen to shift inside a palletized container composed of these frame parts, they will not catch on any projections. There are no projections on any of the parts, and thus no water or dirt can collect. The creation of xe2x80x9cpuddlingxe2x80x9d areas is prevented. Simple cleaning is possible. In addition, a good visual impression is created.
The frame can be realized so that a wall belonging to one of the frame bars and comprising the locking recess makes an acute angle with a direction of insertion of the frame insert. Owing to the presence of an acute angle or an edge that slopes upwardly in the opposite direction to the direction of insertion of the frame insert, the frame insert is prevented from being pushed on through as it is inserted into the frame and a form-fit is created in the pushing direction. This is true in particular if the walls of two mutually parallel frame bars each make an acute angle with a direction of insertion of the frame insert, in a practically mirror-inverted arrangement. The distances between the frame bars at the two terminal edges of the confronting parallel walls are therefore different. The direction of insertion is preferably the direction in which the planes become narrower.
The frame is advantageously realized so that the inserting edges of the frame insert engage the locking recess under prestress. This provides additional retention, in addition to the form-fit of the locking recess, by increasing the static friction as a result of a pressure stress excited transversely to the loading direction. This stress can be adapted to the loading requirements concerned, for example in the shipping of goods. The use of a prestressed frame insert is especially advantageous in the case of metals or other relatively elastic materials.
It is advantageous that the inserting edges of the frame insert make an acute angle with the direction of insertion that is quantitatively greater than the acute angle of the frame-bar wall comprising the locking recess which they are to engage. This provides a simple way of generating. tension with the frame insert in the inserted state. This is advantageous for improving the retention of the frame insert, especially in the case of metal sheet.
An advantageous embodiment of the frame consists in that the frame insert is inserted by a planar or offset inserting edge into a locking recess realized as a push-in slot. This type of joint, particularly as a complement to the oblique walls on the insertion sides of the other frame bars of the frame, provides a way of securely positioning a frame insert, during the production of the frame, before the other edges of the frame insert are inserted. An offset inserting edge provides, in particular, a smooth edge at the transition from the frame insert to the frame bar.
It is advantageous if the frame insert only partially fills the surface of the frame. This makes it possible for the goods being carried to be ventilated or to be observed and monitored. In particular, a savings in material is possible and the gross weight is reduced. Furthermore, the assembly of the frame insert is facilitated by the lower press-in forces that need be applied.
The frame can be realized so that the frame insert is multi-part and its parts are distributed evenly over the surface of the frame. The multi-part nature of the frame insert makes for a wider range of variation in configuring the arrangement. If slidable frame inserts are used, the inserts can be arranged differently, as needed, even after assembly. An even distribution of the frame-insert parts over the surface of the frame creates uniform absorption of the forces that must be withstood during the use of the frame, e.g. as a palletized container. In addition, an appealing visual impression is ensured.
The frame insert advantageously is a hollow-profile section whose ends engage locking recesses of the frame bars. The realization of the frame insert as a hollow-profile section ensures good stability against both transverse and longitudinal forces, while keeping weight to a minimum, Materials usage is minimal, and the hollow-profile section can readily be fabricated in a proven manner by extrusion. When the frame insert is pressed in, the hollow-profile section also absorbs elastic deformation forces at the edges of the frame insert. Thus, constant, consistent prestressing of the frame insert is not necessary in every case, but instead, the hollow-profile section can serge to compensate for deviations resulting, for example, from the use of diverse materials or shapes. The hollow-profile section enables the frame with frame insert to be used as a thermally insulating wall for temperature-sensitive perishable goods. In addition, the use of multi-part frame inserts distributed over the surface of the frame is especially advantageous with this hollow-profile form, since the end edges can be interlocked securely even when the contact surface is small.
It is advantageous if the inserting edge of the frame insert is placed in an undercut in the frame bar. The undercut provides better retention to keep the frame insert from, slipping out against and transversely to the direction of insertion. In this case the acute angle does not necessarily have to be selected to achieve optimum retention, but can be adapted to simpler production conditions. During use of the frame with the frame insert, for example as a palletized container for carrying heavy, unwieldy goods, the franc inserts are secured against being pressed out by any shifting of the goods during transport.
If the frame insert is braced against its direction of insertion to prevent it from being pushed on through, this provides an advantageous embodiment of the frame. Otherwise, if, for instance, the frame-bar wall provided with the interlocking device is set at a low angle, the frame-insert part can accidentally be pushed on through the frame during assembly and fail to find support.
It is advantageous if the frame bars comprise supporting projections that extend behind the frame insert. Such supporting projections can easily be produced on frame hollow-profile sections by coextrusion, and can be shaped so that while ensuring effective retention, they do not present a hindrance to goods being slid into and moved about in a palletizable container composed of the frame and the frame inserts.
The frame can be realized so that the locking recesses keep the frame insert aligned with walls of the frame bars. This type of construction ensures that goods will not become caught on one another while being pushed into the container and that no hard-to-remove dirt can attach itself to the frame with frame insert.
It is advantageous if the frame bars and/or tile frame insert are made of metal or plastic. The use of metal or plastic ensures that palletizable containers constructed of these frames and the frame inserts are easy to clean and are safe and hygienic. Furthermore, metal or fiber-reinforced-plastic construction is, in particular, very resistant to the effects of external and internal forces. Plastic makes for very light-weight construction, which is especially suitable for air transport. It is also advantageous to construct a frame with frame insert of a combination of various materials. Due to the interlocking connection, an extremely wide variety of materials can readily and advantageously be used in combination as frame inserts and frames.
A further advantageous embodiment of the frame is realized if two or more frames are connected by a coupling/cooperative-coupling mechanism consisting of a channel section disposed on a frame outer wall of a first frame and a fillet disposed on a frame outer wall of a second frame and pushed into said channel section. This permits a widely variable mode of construction for different containers and frame structures. The construction of the coupling mechanism from channel sections and inserted fillets ensures stable retention and effective sealing against the ingress of moisture. The simplicity of assembly affords the possibility of stacking container frames to save space when the container is not needed for a time.
In order to produce a frame from plural frame bars with a frame insert in which the frame bars are connected to one other at their ends and the frame insert is mounted between the frame bars in such a way that it can be loaded transversely to the plane of the frame, a method as recited in claims 1 to 20 is proposed. The object is to find a simple, cost-effective joining method for producing frames with frame inserts.
This object is accomplished in that the frame insert is pushed between the frame bats transversely to the plane of the frame and is thereby interlocked with locking recesses of these frame bars in a transversely form-fitting manner. In contrast to welding or riveting, this interlocking can be achieved in one operation without expensive implements. The joining method of interlocking makes it possible to assemble a very wide variety of frame inserts and frames with one machine. This joining technique offers the particular advantage in production that the frame insert can be connected to the frame in a simple manner. No heightened requirements need be imposed on surface finish or on the choice and properties of the materials used in the elements for assembly. The method does not exclude the possibility of using other customary joining methods complimentarily and for better retention.